1. Field of the Invention
The present invention is directed to a substrate processing apparatus for processing a substrate in a plurality of processing units in a predetermined order by transferring the substrate between said plurality of processing units. The present invention is also directed to a device for and a method of transferring substrates in the substrate processing apparatus by removing a processed substrate from a processing unit and by inserting a substrate to be processed to the processing unit, such as a resist coating device, substrate cleaning device, substrate developing device, substrate heating device, substrate cooling device, exposing device and so on.
2. Description of the Background Art
In manufacturing fine electronic substrates such as liquid crystal displays and semiconductor devices, it is necessary to have a plurality of processing units described above and a transferring device, which transfers substrates such as glass substrates for liquid crystal displays or semiconductor wafers to the plurality of processing units in a predetermined order.
In one prior art apparatus, all of the plurality of processing units are arranged in a horizontal row on a floor. However, this arrangement of processing units causes an increase of the floor area required for the apparatus by increasing total length of the apparatus, since many processing units are necessary for manufacturing fine electronic substrates such as liquid crystal displays and semiconductor devices. This arrangement has the further disadvantage of being difficult to modify, from a predetermined order, the order of processing units in which a substrate is processed, since the substrate transferring device of this arrangement is designed to transfer a substrate in a predetermined order in a specified direction. It is difficult to change such predetermined order and/or such specified direction. That is, for transferring the substrate in a different order from said predetermined order, the substrate must be transferred in the opposite direction to said specified direction or must bypass a specified processing unit. This transferring causes interference between a plurality of substrates transferred in series.
U.S. Pat. No. 4,985,722 discloses a second prior art apparatus in which a plurality of processing units are arranged in two laterally spaced horizontal rows spaced in parallel with each other, and a substrate transferring device is positioned in the space formed between the two horizontal rows. In this second prior art apparatus, it is easy to modify, from a predetermined order, the order of those processing units in which a substrate is processed, because such modification is achieved by a change of action of the substrate transferring device without modification of arrangement of the processing units. The total length of the apparatus of the second prior art apparatus is shorter than that of the first prior art, since the plurality of processing units are arranged in two horizontal rows. However, the floor area required for operating the apparatus of the second prior art is not reduced in comparison with that of the first prior art, since the apparatus of the second prior art is different from that of the first prior art only in the arrangement of the plurality of processing units.
Furthermore, in the second prior art apparatus, the check and/or repair of the substrate transferring device is difficult, since it is positioned between the two horizontal rows. The second prior art apparatus has the further disadvantage that the time required for exchanging substrates in a processing unit increases. That is, in the second prior art apparatus, a processed substrate is taken out of a processing unit, and a next substrate, which has not been processed in that processing unit, is taken into the processing unit thereafter.
Japanese Laid-Open Patent Application No. Sho63-5523 discloses a third prior art apparatus in which a plurality of processing units are arranged vertically one by one and a substrate is transferred only in the vertical direction.
This arrangement embodied in the third prior art apparatus can reduce the floor area required for the apparatus in comparison with apparatus of the first and second prior arts. However, the height of the third apparatus increases, especially for apparatus including a large number of processing units. Therefore, in the third prior art apparatus, the number of processing units included in the apparatus must be limited by the ceiling height of factory in which the apparatus is to be installed. In the arrangement disclosed in the third prior art it is also inconvenient to check and/or repair a processing unit arranged at or near the top of the apparatus.
Because some of the processing units included in this type of apparatus are heavy and/or require many pipes for supplying a plurality of different treating liquids, such processing units should not be arranged at relatively high locations. Therefore, the arrangement disclosed by the third prior art is a poor design choice. Similar to the first prior art apparatus, this third apparatus has the further disadvantage that it is difficult to modify, from a predetermined order, the order of those processing units in which a substrate is processed. In the third prior art apparatus, the substrate transferring device, for transferring the substrate between the plurality of processing units, transfers the substrate vertically by relatively long distances. The particles generated by such transference of the substrate settle on the processing units disposed at relatively low positions, causing contamination of such processing units and substrates thereat. The substrate transferring device used in the third prior art apparatus must transfer a large number of substrates only in a vertical direction, many of the transferring paths necessary for transferring substrates from a specified processing unit to the next specified processing unit, must be designed for avoiding interference between all of the transferring paths. This serves to increase the time required for processing a substrate in all of the processing units in a predetermined order.